1. Field of the Invention
The present invention relates to an apparatus, a mechanism, and a process for warming-up a fuel cell in order to start a cold fuel cell. More particularly, the invention concerns an apparatus, a mechanism, and a process for warming-up a fuel cell utilizing a hydrogen-occlusion alloy to start a fuel cell under a condition of low temperature.
2. Description of Related Arts
In recent years, fuel cell electric vehicles (hereinafter abbreviated as “FCEV”) have drawn attraction from ecological viewpoints, due to the understanding that the amount of carbon dioxide exhausted, which leads to global warming, should be suppressed. A FCEV carries a fuel cell (hereinafter abbreviated as “FC”), which generates power due to electrochemical reaction between hydrogen (H2) and oxygen (O2) in air, and supplies the power generated from FC to a driving motor at which driving force is brought about.
A FC exhibits its performances at the fullest extent at a given temperature. For example, in the case of a proton exchange membrane (PEM) type FC, the temperature for which FC exhibits the best performances is approximately 80° C., and if the temperature is lower than this, the power generation performance (electromotive force) is decreased. For this reason, in order to start FC at a winter season or at a cold district, FC should be warmed-up (i.e., FC should be heated to a prescribed temperature).
The conventional warming-up of FC is conducted as follows:
(1) Warming-up of FC through Heater:
An electric heater is heated by a battery possessed by a FCEV or a commercial electric power source provided on a garage or such to warm-up FC through the heat thus generated.
(2) Warming-up of FC through Hydrogen Combustor etc.:
Hydrogen or methanol (or gasoline) possessed by a FCEV as a fuel (raw fuel) is supplied to and combusted in a catalytic combustor etc., the combustion heat being utilized to warm-up the FC.
(3) Warming-up of a FC utilizing Heat generated by the FC Itself:
Heat generated due to the electrochemical reaction between hydrogen and oxygen (so-called self heating of FC) at starting the power generation of FC is used to warm-up FC.
(4) Other Processes for Warming-up a FC:
A heat accumulating agent or a heating agent is utilized to warm-up a FC.
However, the warming-up of FC through the electric heater described under Item (1) suffers from the drawback in terms of consumption of the battery. Also, at a low temperature, sufficient power can be supplied from the battery in some cases. In the case of utilizing the commercial electric power source, a FC cannot warm-up at a portion where no commercial electric power source is provided, such as on the road. In the case of warming-up of a FC through the hydrogen combustor or such described under Item (2), the fuel (raw fuel), which should be used for the power generation of the FC, is unduly consumed. In the case of the warming-up of a FC utilizing the heat generated by the FC itself, the FC cannot be warmed-up under the situation where the FC cannot generate power. Also, the consumption of the fuel (raw) for warming-up a FC is not preferable. The use of the heat accumulating agent or the heating agent mentioned under Item (4) has drawbacks, including that it is difficult to take heat at a necessary time and the heat accumulating agent or a heating agent can be repeatedly used only with difficulty. That is, in the prior art, energy exclusively used for warming-up a FC is required or energy, which should be used in the power generation, is wasted. Also, the use of the heater or the hydrogen combustor, etc, which can only be used in the warming-up, and the use of specialized heat accumulating agent or heating agent are problematic in terms of enlarging the fuel cell system. The warming-up of a FC should be conducted rapidly, which requires a large quantity of energy or an enlarged warming-up apparatus. However, the warming-up of a FC must also be carried out in a simple configuration with ease. These problems are applicable to a hydrogen automobile, which carries an internal combustion engine (apparatuses consuming hydrogen) utilizing hydrogen as fuel.